Association between Proteinuria and Risk of Chronic Inflammatory Demyelinating Polyneuropathy/Multifocal Motor Neuropathy: A Nationwide Population-based Cohort Study.

BACKGROUND

This study aimed to determine whether proteinuria is associated with the subsequent development of chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN).

METHODS

We conducted a population-based retrospective cohort study using the Korean National Health Insurance Service database. Individuals aged ≥ 20 years who underwent national health screening in 2009 (N = 3,937,902) were followed until December 2020. Participants with a prior history of CIDP/MMN or diagnosis within one year of screening were excluded. Proteinuria was assessed via urine dipstick (positive ≥ 1+). The primary outcome was incident CIDP/MMN, defined by the concurrent presence of ICD-10 code G61.8 and Rare and Intractable Disease program code V126. Cox proportional hazards models examined the association, adjusting for potential confounders.

RESULTS

At baseline, 2.5% of individuals had proteinuria. During follow-up, 210 individuals developed CIDP/MMN. The incidence rate was significantly higher in those with proteinuria (1.44 per 100,000 person-years) than in those without (0.50 per 100,000 person-years). After adjustment for demographics, lifestyle, and comorbidities, proteinuria remained significantly associated with increased CIDP/MMN risk (adjusted hazard ratio 2.32; 95% confidence interval 1.35-4.03). This association was consistent across subgroups defined by sex, age, and chronic kidney disease.

CONCLUSION

Proteinuria is associated with a modest risk of developing CIDP/MMN. These findings suggest possible shared immunopathologic mechanisms involving antigens or immune pathways common to both the kidney and peripheral nerves. Neurologic monitoring may be warranted in individuals with proteinuria.